Uncertainties in particle size distributions measured with ratio-type single particle counters

Abstract

Analysis of the light scattered by individual particles passing through a focused laser beam has recently become a common technique for characterizing air pollution aerosols. Early optical particulate analyzers utilized the light scattered in a single field of view to classify particles by size, but were hampered by relatively low resolution. This was due to effects of the index of refraction on the functional dependence of the scattered intensity on particle diameters1 and to variations in incident light intensity within the sensitive volume, which is Gaussian for laser beams.